I guess it is that UK bi-metal coin; I got it in pocket change a while ago.
It reads 'An act for the abolition of the slave trade' and has a central 1807 date merged with a broken chain. Incidentally, might be a Numista record for reviving an old Topic, from three years two weeks ago! Thanks
https://en.numista.com/catalogue/pieces10600.html
Will see if I can find the asked-for information ...
http://www.royalmint.com/discover/uk-coins/coin-design-and-specifications/two-pound-coin
http://en.wikipedia.org/wiki/Two_pounds_%28British_coin%29
"1807 - 2007 The Abolition of the Slave Trade
Although slavery itself was not abolished, and indeed still proliferates in many areas of the world, this coin recognises the abolition of the slave trade in Britain."